The present invention relates to a manhole cover receiving frame for underground structures such as manholes for water supply and sewage systems, and manhole structures for fire hydrants, etc.
A conventional underground structure, for example, a cover receiving frame of a manhole for water supply and sewage systems is provided in a manhole tube. Therefore, when the road surface is not level with the upper surface of the manhole cover receiving frame, a level adjusting ring must be inserted between the manhole tube and the manhole cover receiving frame or a ring must be removed therefrom. However, this operation is not only cumbersome but also is time consuming.
In the case where the level of the manhole cover receiving frame must be adjusted to match the level of the surrounding road surface, the traffic must first be stopped, after which the following tasks must be are carried out sequentially:
(A) cutting an existing pavement PA1 (B) lowering the existing pavement PA1 (C) digging operation PA1 (D) removal of a cover receiving frame PA1 (E) installation of an adjusting ring PA1 (F) installation of a cover receiving frame PA1 (G) adjustment of the level of roadbed PA1 (H) transfer of the pressure of roadbed PA1 (I) temporary pavement PA1 (J) final pavement
These tasks are troublesome and are time consuming, thus increasing costs.
So, with roads having heavy traffic, a traffic jam is created due to the level adjustment work. Development of a method for simply finishing the level adjustment work has been desired.
Further, it takes a large amount of time to adjust an angle of inclination for matching the upper surface of the manhole cover with the inclination of the road surface. Therefore, development of measures capable of carrying out the adjusting operation in a short period of time have been desired.